The present invention relates to the manufacture of incandescent lamps, more specifically, the present invention relates to the manufacture of incandescent lamps having a press-sealed base.
For many years incandescent lamps used in automobiles have been mounted in sockets by means of metal bases formed as a part of the lamp. For some time now, the use of baseless press-sealed lamps has become common in automotive applications. The elimination of the metal base and the manufacturing machinery needed to attach the metal base to the lamp have resulted in substantial cost savings.
Until very recently the use of baseless press-sealed lamps in automotive applications has been confined to those lamps having a single filament. The key difficulty in developing a baseless press-sealed dual filament lamp has been the lack of a practical means of securing the lamp to a mounting socket in the automobile. Such difficulty is caused by the semi-cylindrical hump appearing on either side of the flattened base portion of a baseless press-sealed lamp. This semi-cylindrical hump is formed on the base during the manufacturing process to maintain an internal passageway for the evacuation of gases from the bulbous portion of the lamp.
The presence of this semi-cylindrical hump, necessitated by the need for a gas evacuation passageway, creates difficulties in the design of an appropriate socket for baseless dual filament press-sealed lamps. These difficulties are caused by the limited space available for the terminals necessary to make electrical connections to the lamp. There is, therefore, a need in the art to develop a way to manufacture baseless press-sealed incandescent lamps that do not have a semi-cylindrical hump on either side of the flattened portion of the press-sealed lamp base.